The invention relates to a device for interrupting the feed of a roving to a drawing frame. A feed roller pair associated with the drawing frame includes a powered bottom roller and a top roller tensioned against the bottom roller by springs. A clamp is arranged in such a manner that it is introduceable from the feed side between the top roller and bottom roller for lifting the top roller away from the bottom roller and clamping the roving against the circumference of the top roller when a break is detected in the roving.
In a known device for interrupting the feed of a roving, German Offenlegungsschrift No. 30 48 481, an arcuate-shaped clamp is mounted on the bottom roller, the clamp being entrained in the circumferential direction by the bottom roller with the clamp being introduceable between the bottom and the top roller when a yarn break occurs. When the clamp is introduced between the top and bottom roller, the top roller is lifted away from the bottom roller and the roving is clamped against the circumference of the top roller. For structural reasons, clamping segments of this type are necessarily so light in construction that they are suitable only for relatively thin rovings. Accordingly, clamping segments of this type have been found to be not sufficiently operationally reliable for heavier rovings, for example, when used in yarn spinning machines.
In another known device for interrupting feed of a roving, German Offenlegungsschrift No. 29 52 533, a pivoted lever can be disposed in the vicinity of the feed roller pair of a drawing frame with the rotational axis of the lever running parallel to the feed rollers. This pivoted lever is designed as a lifting element, e.g., in the form of a wedge, and engages the top roller to thereby lift the top roller away from the bottom roller. A clamping pin for abutting the circumference of the top roller is provided on the pivoted lever and serves to clamp the roving. In this device, the top roller is supported at two points when roving feed is interrupted, namely at its axis and at its circumference, which may create difficulties if the two supporting elements are not properly aligned with one another. In particular, if the clamping pin is not pressed with sufficient force against the circumference of the top roller, there is a danger that the roving feed will not be effectively interrupted. Consequently, it is necessary in this device to provide the maximum possible actuating force.